Persistent epithelial defects (PED) of the cornea are uncommon, but in addition to the immediate adverse effect on vision, persistent defects can have serious consequences for the health of the eye including infection, scarring, melting, and even perforation. Several etiologies for PED include dry eyes, corneal epithelial stem cell deficiency, diabetic keratopathy, and neurotrophic keratopathy secondary to corneal transplant surgery or herpetic infections. In general, traditional therapy of PED consists of aggressive lubrication with preservative-free artificial tears and ointments, the use of bandage soft contact lenses, pressure patching, punctal plugging, and the surgical closure of the eyelids. Unfortunately, the success rates with these conventional treatment modalities are varied, and overall, disappointingly low. As such, much research is currently being directed at finding better treatments for PED. Nexagon is a novel therapeutic agent that has been shown to be effective in treating skin lesions, and it has been shown in animal studies and in preliminary human studies to be safe and efficacious in treating PED. The primary objective of this prospective, Phase 2, double-masked, vehicle-controlled study is to evaluate the efficacy and safety of Nexagon (10 [unreadable]g) in the healing of persistent corneal epithelial defects (PED) that have resulted from corneal epithelial debridement during diabetic vitrectomy surgery. Fifty-two patients will be randomized in a 1:1 fashion for vehicle only compared to the active drug. Patients will be followed according to a detailed study schedule, with up to 4 weekly applications of the vehicle/drug permitted. The primary outcome measure for this study will be the percent reduction in epithelial defect size from baseline to Day 14. If Nexagon can be shown to be effective in healing PED in these circumstances, it would be a powerful therapeutic option in the prevention of the serious morbidity that can result from PED. The results of this study could therefore support and lead to the commercialization of this non-surgical method for enhancing epithelial wound healing, which could ultimately benefit nearly 23,000 corneas in the United States annually.